如何從用戶定義的Neo4j功能

Question

返回對象我有這樣一個複雜的查詢：

MATCH path = allShortestPaths(...) 
WITH path, reduce(x={ 
      specificStamp: "", 
      specificCount: 0, 
      ... 
     }, 
     r IN relationships(path) | 
      CASE WHEN ... 
       THEN { 
        specificStamp: some-expr(x), 
        specificCount: another-expr(x), 
        ... 
       } 
      ... 
      END 
     ) AS pobj 
ORDER BY pobj.specificStamp, pobj.specificCount 
RETURN head(COLLECT(path)) AS path, pobj.specificStamp AS stamp, COUNT(*) AS cnt 
ORDER BY length(path), stamp 

在真正的代碼的邏輯是比較複雜的，包括嵌套CASE和多用一些複製表達式THEN複雜。 ..

爲了簡化問題，最好將reduce邏輯放入單獨的函數中。但Neo4J用戶定義的函數只能返回一個值。

哪種返回值對應於此密碼錶達式：{specificStamp: "", specificCount: 0}？可以是Object？但根據documentationObject意味着ANY類型。

可能是Map？但是，哪個地圖模板？ Map<String,String>衝突與Map<String,Integer>

Answer 1

返回Map<String,Integer>或Map<String,Object>

看到這對有效類型：https://neo4j.com/docs/developer-manual/current/extending-neo4j/cypher-functions/#writing-udf

Answer 2

Map<String,Object>是不夠好。

不需要Cypher查詢中的附加類型轉換。 來自用戶函數的字符串字段以字符串形式出現。只要長久。